BAY-850

The discovery of BAY-850 was facilitated by optimisation of hits from a DNA encoded library screen. It shows remarkable specificity for the ATAD2 BD and does not interact with the closely related ATAD2B BD. This may be explained by a non-canonical binding mode which results in ATAD2 protein dimer induction.

BAY-850 was identified from a DNA Encoded Library screen and optimised to what appears to be a useful ATAD2 probe with impressive selectivity both within the target class and more broadly. Notably, BAY850 shows selectivity over ATAD2B which differentiates it from GSK8814. Data are presented which show that BAY-850 induces dimerization of ATAD2 and prevents association with chromatin. A Fluorescence Recovery After Photobleaching (FRAP) assay was used to confirm displacement of FL ATAD2 from chromatin in cells. Single-digit uM activity was observed in antiproliferative cellular assays, however, the cytotoxic effects could not be unambiguously linked to ATAD2 BD inhibition.

It is unclear whether the cytotoxicity observed between 5-10 uM is a result of on-target effects of ATAD2 inhibition. Thus, concentrations, where cell toxicity is observed, should not be the primary determinant for recommended concentrations for use in cells as is listed above. Rather, the 1 uM dose used in the FRAP experiments effectively displaces the ATAD2 BD from chromatin, displays no cytotoxicity in HMEC cells, and maybe a better concentration for cellular studies.
I recommend starting with a 1 uM dose of the compound in cell systems. If increasing dose, take care to assess viability effects. Especially in cancer cell lines, genetic loss of ATAD2 has only modest effects on cell proliferation (see depmap.org), so considerable viability effects in a given cell type at doses higher than 1 uM may be indicative of off-target effects.